Method of using photographic vesicular and diazo films having diazo antihalation layers



Sept. 9, 1969 E. R. SKARVINKO 3,466,172

METHOD OF USING PHOTOGRAPHIC VESICULAR AND DIAZO FILMS HAVING DIAZO ANTIHALATION LAYERS Filed Jan. 13, 1967 VESICULAR 0R DIAZO EMULSION F|G.1

SUPPORT VESICULAR FIG. 2

SUPPORT ANTI-HALATION E LAYER F l G 3 -/SUPPORT ANTI'HALATION LAYER INVENTOR EUGENE R. SKARVINKO BY #1444 d yin...

AGENT q nited States Patent 01 3,46%,172. Patented Sept. 9, 1969 dice US. Cl. 96-49 3 Claims ABSTRACT OF THE DISCLOSURE A process of forming either an azo dye or a vesicular image in photographic elements which have an antihalation layer which can be rendered inert by overall exposure to actinic light after imaging said element.

The invention relates to photographic elements of the vesicular and diazo type. More particularly, the invention relates to vesicular and diazo image forming elements wherein there is included an antihalation layer which can be removed by means other than those employing wet solotions, and to photographic process utilizing said elements.

The art is familiar with photographic elements which have antihalation layers. The antihalation layers are comprised of a water-permeable colloid layer containing a dischargeable dye that absorbs light of wavelengths to which an emulsion layer is sensitive. This light absorbing dye prevents halation (i.e., the spreading of light beyond a desired boundary), thereby increasing the resolution of the developed film. It is necessary that the antihalation layer be removed from the developed film, for if it is not removed, the developed film becomes stained or discolored due to the presence of the light absorbing dye. The dyes are normally discharged during photographic processing in an aqueous developing and/or fixing bath.

While the art is familiar with antihalation layers in those photographic elements of the silver halide emulsion type, it is not familiar with vesicular photographic elements having antihalation layers. In such photographic elements, vesicular images are formed in a light sensitive layer comprising a thermoplastic composition having dispersed therein units of photolytic material. These units of photolytic material upon exposure to actinic radiation will generate units of gas which subsequently form vesicules within the thermoplastic compositions. It is these vesicules that form the desired image. Heretofore, very high resolution of the developed image was not obtainable since it was not practical to include an antihalation in this type of photographic element. The removal of the antihalation layer presents a practical problem since removal thereof is important to prevent staining or discoloration of the developed film. Unlike the silver halide emulsion films, vesicular and diazo images are developed by heat and not by aqueous solutions. Consequently, wet techniques of removal of the antihalation layer as used in the silver halide films are not applicable to vesicular image-forming films. It is therefore necessary and desirable to remove the antihalation layer by means other than by wet techniques to obtain clear and definite images.

It is a primary object of this invention to provide improved vesicular and diazo photographic elements.

Another object of this invention is to provide improved vesicular and diazo photographic elements which when developed exhibit an image of high resolution.

Still another object of this invention is to provide improved vesicular and diazo photographic elements having incorporated thereon antihalation layers which are removable by other than those employing wet chemical methods.

A further object of this invention is the provision for a photographic process utilizing the photographic elements of this invention.

Therefore, in accordance with one aspect of this invention, a photographic element, which comprises a transparent and thermally stable supporting base member having coated on one of its sides an ultraviolet absorbing layer and a vesicular or diazo image-forming layer, is prepared. Alternately, the ultraviolet absorbing layer and the image-forming layer may be on opposite sides of the base member. Subsequent to development of the image or simultaneously therewith, the ultraviolet absorbing layer is removed by exposure to ultraviolet radiation.

Considered from another aspect, this invention relates to a photographic process characterized by the steps of:

(a) Exposing the photographic element of the above paragraph to actinic radiation to effect a latent image;

(b) Developing the latent image by heating said photographic element; and

(c) Subsequently, or simultaneously, exposing said element to ultraviolet radiation, whereby the antihalation layer is removed.

An advantage of this invention is the provision of vesicular and diazo image-forming photographic elements, from which images can be reproduced having the same high degree of definition heretofore obtainable only in silver halide photographic elements.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings and examples.

In the drawings:

FIG. 1 depicts a vertical cross section of a typical prior art vesicular image-forming photographic element having a layer of image-forming material on a base support but lacking an antihalation layer.

FIG. 2 depicts a vertical cross section vesicular imageforming photographic element constructed in accordance with the principles of this invention and which is provided with an antihalation layer on the same side of the base support as is the image-forming layer.

FIG. 3 depicts a vertical cross section of a photographic element constructed in accordance with the principles of this invention which alternately show the antihalation and image-forming layers on opposite sides of the base support.

Now referring to FIGS. 2 and 3, a detailed description of the structure of a vesicular or diazo image-forming photographic element constructed in accordance with the principles of the invention will be undertaken. The element consists of a supporting base member which is adapted to receive the layers of vesicular image-forming material or diazo image-forming material.

The supporting base may be constructed of any suitable material providing it has certain properties. Spe cifically, the support material should be stable over a wide range of temperatures so as not to decompose, degrade or otherwise change its properties, especially its optical characteristics, when subjected to temperatures encountered in various climates in normal usage, and in typical manufacturing, storing, processing and otherwise operations. The support material should also be nonreactive with the vesicular or diazo image-forming layers and generally resistant to acids, bases, and solvents. As for the optical properties of the supporting base, it should be substantially transparent to visible and ultraviolet light, especially if it is desired to use the element as an original for making further copies by the same or other processes. It is alsodesirable that the base exhibit little absorption in the infrared range. This will insure that radiant heat is not absorbed and accumulated in the base causing premature development or otherwise interfering with the exact temperature control which is essential in the processing techniques. A material which has been found to be very suitable for use as a supporting base is the reaction product of ethylene glycol and terephthalic acid, which produces a polyester film made by E. I. du Pont and Co. under the trade name Mylar. The thickness of the base, while in no way being critical, is preferably as thin as is consistent with providing adequate support for the vesicular layer and affording suflicient durability to the composite element.

As indicated previously, the supporting base has dispersed on one of its surfaces a vesicular image-forming layer and on its other surface an antihalation layer. The vesicular image-forming layer comprises a thermoplastic vehicle having uniformly dispersed therein units of photolytic material. The thermoplastic vehicle may be chosen from a variety of classes, regardless of chemical origin, providing it has the requisite physical properties. Specifically, the vehicle should be such that it is sufficiently rigid at room temperatures and throughout anticipated climatic changes to resist deformation, but yet sufiiciently plastic at room temperature that it permits the diffusion of gas units Within the vehicle and ultimate permeation thereof to the surroundings. In addition, the vehicle must soften sufiiciently upon heating to allow any gas units formed to expand in size to form vesicules. The vehicle should also be transparent to visible light.

Photoplastic vehicle materials which are suitable for the above purposes and which exhibit the desired physical properties can be certain natural organic colloids such as gelatin or certain water inert synthetic colloids. Examples of such materials which are immediately available for use in conjunction with a polyethylene terephthalic base material are polystyrene, polyvinyl chloride, copolymers of vinyl chloride, and vinyl acetate. Other vehicle materials, while not directly suitable for ultimate results, are rendered suitable by the addition of modifiers.

The photolytic material suitable for use in this invention should be one that generates a gas upon exposure to light and which can be incorporated into the vehicle either mechanically such as by way of a ball mill or by means of appropriate solvents. Preferably, photolytic materials of the diazo type, which photolytic materials upon decomposition liberate nitrogen gas, are used. Among such preferred substances are P-NN-dimethylaminobenzene-diazonium zinc chloride and 1-dimethylamino-4 naphthalenediazonium fluorborate. Also useful are P- anilinobenzenediazonium sulfate, P-N,N'-diethylaminobenzenediazonium zinc chloride, P(N-ethyl-N-hydroxyethylamino) benzenediazonium zinc chloride, P(N-ethyl- N-methylamino) benzene-diazonium zinc chloride, 4-diazo-3-oxynaphthalene sulfonic acid, and 4-NN-diethylamino-5-methylbenzenediazonium chloride.

When a diazo photographic element is to be prepared, the supporting base may have coated thereon an imageforrning layer comprising one of the above diazo materials and a coupler. The coupling compound used in this invention is of the type generally employed in the manufacture of light-sensitive diazotype layers. These couplers may be those containing a phenolic hydroxyl group or an active methylene group. Examples of such couplers are: 2,3 naphthalenediol, 6,7 dihydroxynaphthalene-Z- sulfonic acid, N-o-methoxyphenyl 3 hydroxy-i-naphthamide, 4,4 diresorcinol, N-o-tolyl-3-hydroxy-2-naphthamide, l-naphthol 3 sulfo-namide, 1-phenyl-3-methyl-5- pyrazolene, acetoacetanilide, acetoacet-o-toluidide, and the like.

The sensitizing composition, in addition to the diazonium compound and the azo coupling compound, also contains the usual adjuncts designed to effect stabilization such as thiourea, thiosenamine, and the like.

The above components, prior to application, are dissolved in suitable solvents such as water, isopropyl alco- .4 hol, butyl alcohol, acetone, methanol, methoxy methanol, Z-methoxyethyl acetate and the like.

Desirable U.V. absorbing materials are light sensitive diazonium compounds such as the diazo oxide or as a metallic double salt such as zinc chloride double salt or the like and are derived from aromatic paradiamines, N-mono or di-substituted benzene paradiamines or from para-amino diphenylamine. Many of the above mentioned diazo compounds used in the image-forming layer may be used. The criterion for choosing the U.V. absorbent is that it should absorb light having about the same energy as that used for exposing the image-forming layer.

The U.V. absorbent is combined in a film forming solution including a thermoplastic binder such as polyvinylidene, acrylics and the like; a suitable solvent and, if desired, a cross-linking agent.

The antihalation layers are prepared by dispersing from about 6% to 8% of diazo light absorbing material, based on the total solids of the layer in a plastic material, such as Saran F120, a copolymer of vinylidene and acrylonitrile, sold by E. I. du Pont de Nemours. There is also included from 30% to 50% by weight of polymeric esters of acrylic and methacrylic acids marketed by Rohm and Haas as a 40% solution in methyl ethyl ketone under the trade name Acryloid 101. Acryloid 101 acts as a modifier controlling gas permeability, i.e., allows nitrogen gas to escape after the diazo light absorbing material has been decomposed by actinic radiation.

The following examples more specifically illustrate the invention. It is not intended that the invention be limited to the exact compositions shown. Rather, it is intended that all equivalents to those skilled in the art be included within the scope of the invention as claimed.

Example 1 A vesicular emulsion layer is prepared by dissolving ten parts by weight of F-120 Saran resin, a copolymer of vinylidene acrylonitrile, sold by Du Pont Company, in 60 parts of methyl ethyl ketone. While stirring, 32 parts of Acryloid 101 (polyesters of acrylic and methacrylic acids, sold by Rohm and Haas Company) are added to methyl ethyl ketone to thus obtain a 40% solution thereof. The above solutions are combined and 08 part of p-diazo-dimethylaniline-zinc chloride, a photolytic compound dissolved in six parts of acetonitrile, are added to the same while continuously stirring the solution. This composition is coated on a Mylar base to a thickness of approximately 0.4 mil. The vesicular emulsion coating is heated to a temperature of about 220 F. in air for 5 minutes, treated for 20 seconds in a water bath containing 1% by volume of Photo Flo 200 (sold by Eastman-Kodak Company) and dried at to F.

An antihalation solution is prepared containing:

Grams Saran F 40 Acryloid 101 100 p-Diazo-dimethylaniline-zinc chloride 5.6 Methyl ethyl ketone 143 Acetonitrile 39.6

The above antihalation solution is coated on the surface of the Mylar backing opposite to that of the photolytic emulsion. The antihalation coating is dried at 100 to 110 F.

The prepared film is exposed to ultraviolet radiation, having wavelengths of from 320 to 430 millimicrons, through a suitable positive or negative transparency. Fol lowing this, the film is developed in a heat developer consisting of two rotating rubber rollers at a temperature of about 240 F. The developed film is then re-exposed to ultraviolet radiation of the same wavelength as above for about 1 minute to remove the light absorbing diazo compound in the antihalation layer.

The film is exposed for 2 seconds in a resolution testing apparatus, containing a HBO 220 w./2 mercury arc lamp made by the Osram Company in Germany. The resolving power of the film of this invention was 221 lines per millimeter. Whereas a film prepared similarly but without the antihalation layer had resolving power of only 177 lines per millimeter.

Example 2 The vesicular photographic element of Example 1 except that the vesicular layer is coated on the surface of the antihalation layer.

Example 3 A diazo photographic emulsion comprising p-diazo-dimethylaniline-zinc chloride and a naphthol coupler compound is coated on a Mylar base and dried. The antihalation solution of Example 1 is coated on the opposite surface of said Mylar base in the same manner described therein.

The prepared diazo photographic element is exposed to ultraviolet radiation, having wavelengths from 320 to 430 millimicrons, under a pattern. The exposed element is heated in an ammonia atmosphere to develop an image. The developed element is then re-exposed to ultraviolet radiation of the same wavelength as above for about 1 minute to remove the light absorbing diazo compound in the antihalation layer.

Resolution test as done in Example 1 gave like results.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A vesicular photographic process including the steps of:

(a) exposing a photosensitive element to actinic radiation under a pattern, said element comprising a transparent polyester support member having an antihalation layer contiguous with said support member, said antihalation layer comprising a copolymer of vinylidene chloride and acrylonitrile, a mixture of polyesters of acrylic and methacrylic acids and p-diazodimethylaniline-zinc chloride, and a vesicular image forming layer, said vesicular image forming layer consisting of a copolymer of vinylidene chloride and acrylonitrile, a mixture of polyesters of acrylic and methacrylic acids, and p-diazo-dimethylaniline-zinc chloride;

(b) heat developing said exposed element to form a vesicular image in the exposed areas of the vesicular image forming layer;

(c) re-exposing said element overall to actinic light which decomposes said diazo compound in the antihalation layer rendering said antihalation layer inert to subsequent actinic radiation.

2. The process of claim 1 wherein the antihalation layer and the vesicular image-forming emulsion are disposed on opposite sides of the support member.

3. A process of forming azo dye images including the steps of:

(a) exposing a photosensitive element to actinic radiation under a pattern, said element comprising, a transparent polyester support member having coated on one of its surfaces a layer consisting of p-diazo-dimethylaniline-zinc chloride and a naphthol coupler compound, and having coated on the other surface of said support member, an antihalation layer consisting of a copolymer of vinylidene chloride and acrylonitrile, a mixture of polyesters of acrylic and methacrylic acids and p-diazo-dimethylaniline-zinc chloride;

(b) heat developing said exposed element in an ammonia atmosphere to form an azo dye image in the unexposed areas;

(c) re-exposing said element to overall actinic light which decomposes said diazo compound in the antihalation layer rendering said antihalation layer inert to subsequent actinic radiation.

References Cited UNITED STATES PATENTS 1,966,412 7/1934 Krieger 96--75 XR 2,245,628 6/1941 Von Poser et al. 9691 XR 2,501,874 3/1950 Peterson 9675 XR 2,627,088 2/1953 Alles et a1 9684 XR 2,680,120 6/1954 Gregory 9684 XR 2,702,243 2/1955 Schmidt 9633 2,703,756 3/1955 Herrick et al. 9691 XR 2,729,562 1/1956 Zemp 9675 XR 2,950,194 8/1960 Glavin 9675 3,069,268 12/ 1962 Herrick 9675 XR 3,227,555 1/1966 Van Norman 9684 3,215,529 11/1965 Lindquist et al 96-75 XR 3,269,839 8/ 1966 Altman 9684 XR 3,313,626 4/1967 Whitney 9684 XR 3,370,949 2/ 1968 Van Greenland 9675 FOREIGN PATENTS 906,406 3/ 1954 Germany. 1,016,464 6/ 1964 Japan.

NORMAN G. TORCHIN, Primary Examiner C. BOWERS, Assistant Examiner US. Cl. X.R. 

